Deep electromagnetic rebar probe system, and method of using same

Abstract

A method for monitoring a first attribute of a target object within a non-magnetic structure using a first probe coupled to the non-magnetic structure and located proximate the target object at a first detection region, the method includes a) introducing, at the first detection region, a pulsed electromagnetic interrogation signal along the electromagnetic circuit and through the target object using a first transmitter; b) receiving, at the first detection region, a response electromagnetic signal that is induced in the target object and generating a corresponding response electrical signal comprising time information and voltage information using a first receiver; c) determining the first attribute of the target object at the first detection region; d) generating a corresponding first output signal; and e) comparing one of the first output signal and the first attribute, to a stored value for the first detection region to determine if a condition is met.

What is claimed is: 
     
         1 . A system for non-destructively monitoring at least a first attribute of an elongate, target object extending along an object axis and being disposed within a non-magnetic structure, the system comprising:
 an input signal generator configured to generate pulsed voltage electrical signals;   a first probe coupled to the non-magnetic structure and located proximate the target object at a first detection region, the first probe comprising:
 an electromagnetic coupler extending in a coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the coupler direction being generally aligned with the object axis, 
 a first transmitter connected to the electromagnetic coupler and configured to generate first pulsed electromagnetic interrogation signals based on the pulsed voltage electrical signals, and 
 a first receiver connected to the electromagnetic coupler and spaced apart from the first transmitter, wherein the target object, the electromagnetic coupler, the first transmitter and the first receiver form an electromagnetic circuit, and wherein the first transmitter is configured to introduce each first pulsed electromagnetic interrogation signal through the non-magnetic structure and along the electromagnetic circuit and the first receiver is configured to receive a response electromagnetic signal that is induced in the target object and to generate a corresponding response electrical signal comprising time information and voltage information; 
   a processing structure configured to, for each response electrical signal:
 process the response electrical signal to determine the first attribute of the target object at the first detection region based on the time information and the voltage information, and 
 generate a corresponding first output signal; and 
 compare one of the first attribute and the first output signal, to a stored value for the first detection region to determine if a condition is met. 
   
     
     
         2 . The system of  claim 1 , wherein the processing structure comprises a response signal processor configured to:
 process the response electrical signal to determine the first attribute of the target object at the first detection region; and   generate the corresponding first output signal.   
     
     
         3 . The system of  claim 2 , wherein the response signal processor is further configured to:
 compare the one of the first attribute and the first output signal, to the stored value for the first detection region to determine if the condition is met.   
     
     
         4 . The system of  claim 2 or 3 , wherein the input signal generator and the response signal processor are housed within a controller unit. 
     
     
         5 . The system of  claim 2 , wherein the processing structure comprises one or more computing devices in communication with the response signal processor, the one or more computing devices being configured to:
 compare the one of the first attribute and the first output signal, to the stored value for the first detection region to determine if the condition is met.   
     
     
         6 . The system of any one of  claims 1 to 5 , wherein the processing structure is configured to generate a status signal based on the comparing. 
     
     
         7 . The system of any one of  claims 1 to 6 , wherein the input signal generator is configured to generate the pulsed voltage electrical signals automatically according to a pre-arranged schedule, a frequency, or a period. 
     
     
         8 . The system of any one of  claims 1 to 7 , wherein the input signal generator is configured to generate the pulsed voltage electrical signals according to a user input. 
     
     
         9 . The system of any one of  claims 1 to 8 , wherein the stored value is a predefined threshold value. 
     
     
         10 . The system of any one of  claims 1 to 8 , wherein the processing structure is further configured to:
 store each first attribute of the target object at the first detection region, wherein the stored value is a previously-stored first attribute of the target object at the first detection region.   
     
     
         11 . The system of  claim 10 , wherein the previously-stored first attribute of the target object at the first detection region is an initial first attribute of the target object at the first detection region. 
     
     
         12 . The system of  claim 10 , wherein the previously-stored first attribute of the target object at the first detection region is an immediately previous first attribute of the target object at the first detection region. 
     
     
         13 . The system of any one of  claims 1 to 12 , wherein the processing structure is configured to, for each first attribute of the target object:
 compare the first attribute of the target object at the first detection region to the stored value at the first detection region by calculating one of:
 a difference between the first attribute of the target object at the first detection region and the stored value at the first detection region, 
 a percentage change between the first attribute of the target object at the first detection region and the stored value at the first detection region, and 
 a rate of change between the first attribute of the target object at the first detection region and the stored value at the first detection region, 
   to determine if the condition is met.   
     
     
         14 . The system of  claim 13 , wherein the condition is met if:
 the difference,   the percentage change, or   the rate of change,   is greater than or less than a predetermined threshold.   
     
     
         15 . The system of any one of  claims 1 to 14 , wherein the first probe is affixed to a surface of the non-magnetic structure. 
     
     
         16 . The system of any of  claim 15 , wherein the electromagnetic coupler comprises:
 core extender members that extend into an interior of the non-magnetic structure.   
     
     
         17 . The system of  claim 16 , wherein each core extender member extends through an associated bore through the non-magnetic structure. 
     
     
         18 . The system of  claim 16 or 17 , wherein each core extender terminates close to the target object. 
     
     
         19 . The system of  claim 16 or 17 , wherein each core extender contacts the target object. 
     
     
         20 . The system of any one of  claims 1 to 14 , wherein the first probe is encapsulated within the non-magnetic structure. 
     
     
         21 . The system of any one of  claims 1 to 20 , further comprising:
 a second probe coupled to the non-magnetic structure and located proximate the target object at a second detection region, the second detection region being spaced along the object axis from the first detection region, the second probe comprising
 a second electromagnetic coupler extending in a second coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the coupler direction being generally aligned with the object axis, 
 a second transmitter connected to the second electromagnetic coupler and configured to generate second pulsed electromagnetic interrogation signals based on the pulsed voltage electrical signals, and 
 a second receiver connected to the second electromagnetic coupler and spaced apart from the second transmitter, wherein the target object, the second electromagnetic coupler, the second transmitter and second receiver form a second electromagnetic circuit, and wherein the second transmitter is configured to introduce each second pulsed electromagnetic interrogation signal through the non-magnetic structure and along the second electromagnetic circuit and the second receiver is configured to receive a second response electromagnetic signal that is induced in the target object and to generate a corresponding second response electrical signal comprising time information and voltage information. 
   
     
     
         22 . The system of  claim 21 , wherein the processing structure is further configured to, for each second response electrical signal:
 process the second response electrical signal to determine the first attribute of the target object at the second detection region based on the time information and the voltage information,   generate a corresponding second output signal, and   compare one of the first attribute at the second detection region and the second output signal, to a stored value for the second detection region to determine if the condition is met.   
     
     
         23 . The system of  claim 21 , further comprising second processing structure configured to, for each second response electrical signal:
 process the second response electrical signal to determine the first attribute of the target object at the second detection region based on the time information and the voltage information,   generate a corresponding second output signal, and   compare one of the first attribute at the second detection region and the second output signal, to a stored value for the second detection region to determine if the condition is met.   
     
     
         24 . The system of any one of  claims 21 to 23 , wherein the first probe and the second probe are configured to be operated simultaneously, such that the first probe and the second probe generate the first output signal and the second output signal simultaneously. 
     
     
         25 . The system of any one of  claims 1 to 20 , wherein the system further comprises:
 a second elongate, target object extending along a second object axis and being disposed within the non-magnetic structure; and   a second probe coupled to the non-magnetic structure and located proximate the second target object at a second detection region, the second probe comprising:
 a second electromagnetic coupler extending in a second coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the second coupler direction being generally aligned with the second object axis, 
 a second transmitter connected to the electromagnetic coupler and configured to generate second pulsed electromagnetic interrogation signals based on the pulsed voltage electrical signals, and 
 a second receiver connected to the electromagnetic coupler and spaced apart from the second transmitter, wherein the second target object, the second electromagnetic coupler, the second transmitter and the second receiver form a second electromagnetic circuit, and wherein the second transmitter is configured to introduce each second pulsed electromagnetic interrogation signal through the non-magnetic structure and along the second electromagnetic circuit and the second receiver is configured to receive a response electromagnetic signal that is induced in the second target object and to generate a second corresponding response electrical signal comprising time information and voltage information. 
   
     
     
         26 . The system of  claim 25 , wherein the processing structure is further configured to, for each second response electrical signal:
 process the second response electrical signal to determine the first attribute of the second target object at the second detection region based on the time information and the voltage information,   generate a corresponding second output signal, and   compare one of the first attribute at the second detection region and the second output signal, to a stored value for the second detection region to determine if the condition is met.   
     
     
         27 . The system of  claim 25 , further comprising second processing structure configured to, for each second response electrical signal:
 process the second response electrical signal to determine the first attribute of the second target object at the second detection region based on the time information and the voltage information,   generate a corresponding second output signal, and   compare one of the first attribute at the second detection region and the second output signal, to a stored value for the second detection region to determine if the condition is met.   
     
     
         28 . The system of any one of  claims 25 to 27 , wherein the first probe and the second probe are configured to be operated simultaneously, such that the first probe and the second probe generate the first output signal and the second output signal simultaneously. 
     
     
         29 . The system of  claim 25 , further comprising:
 a third probe coupled to the non-magnetic structure and located proximate the target object at a third detection region, the third detection region being spaced along the object axis from the first detection region, the third probe comprising
 a third electromagnetic coupler extending in a third coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the third coupler direction being generally aligned with the object axis, 
 a third transmitter connected to the third electromagnetic coupler and configured to generate third pulsed electromagnetic interrogation signals based on the pulsed voltage electrical signals, and 
 a third receiver connected to the third electromagnetic coupler and spaced apart from the third transmitter, wherein the target object, the third electromagnetic coupler, the third transmitter and the third second receiver form a third electromagnetic circuit, and wherein the third transmitter is configured to introduce each third pulsed electromagnetic interrogation signal through the non-magnetic structure and along the third electromagnetic circuit and the third receiver is configured to receive a third response electromagnetic signal that is induced in the target object and to generate a corresponding third response electrical signal comprising time information and voltage information; and 
   a fourth probe coupled to the non-magnetic structure and located proximate the second target object at a fourth detection region, the fourth detection region being spaced along the second object axis from the second detection region, the fourth probe comprising
 a fourth electromagnetic coupler extending in a fourth coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the fourth coupler direction being generally aligned with the second object axis, 
 a fourth transmitter connected to the fourth electromagnetic coupler and configured to generate fourth pulsed electromagnetic interrogation signals based on the pulsed voltage electrical signals, and 
 a fourth receiver connected to the fourth electromagnetic coupler and spaced apart from the fourth transmitter, wherein the second target object, the fourth electromagnetic coupler, the fourth transmitter and the fourth receiver form a fourth electromagnetic circuit, and wherein the fourth transmitter is configured to introduce each fourth pulsed electromagnetic interrogation signal through the non-magnetic structure and along the fourth electromagnetic circuit and the fourth receiver is configured to receive a response fourth electromagnetic signal that is induced in the second target object and to generate a fourth corresponding response electrical signal comprising time information and voltage information. 
   
     
     
         30 . The system of  claim 29 , wherein the processing structure is further configured to:
 for each second response electrical signal:
 process the second response electrical signal to determine the first attribute of the second target object at the second detection region based on the time information and the voltage information, 
 generate a corresponding second output signal, and 
 compare one of the first attribute at the second detection region and the second output signal, to a stored value for the second detection region to determine if the condition is met; 
   for each third response electrical signal:
 process the third response electrical signal to determine the first attribute of the target object at the third detection region based on the time information and the voltage information, 
 generate a corresponding third output signal, and 
 compare one of the first attribute at the third detection region and the second output signal, to a stored value for the third detection region to determine if the condition is met; and 
   for each fourth response electrical signal:
 process the fourth response electrical signal to determine the first attribute of the second target object at the fourth detection region based on the time information and the voltage information, 
 generate a corresponding fourth output signal, and 
 compare one of the first attribute at the fourth detection region and the fourth output signal, to a stored value for the fourth detection region to determine if the condition is met. 
   
     
     
         31 . The system of  claim 30 , wherein the processing structure is configured to generate a status signal if the condition is met for any one of the first detection region, the second detection region, the third detection region and the fourth detection region. 
     
     
         32 . The system of any one of  claims 29 to 31 , wherein the first probe, the second probe, the third probe and fourth probe are arranged in grid or a geometric array relative to the non-magnetic structure. 
     
     
         33 . The system of any one of  claims 29 to 32 , wherein the first probe, the second probe, the third probe and the fourth probe are configured to be operated simultaneously, such that the first probe, the second probe, the third probe and the fourth probe generate the first output signal, the second output signal, the third output signal and the fourth output signal simultaneously. 
     
     
         34 . A method for non-destructively monitoring a first attribute of a target object that is within a non-magnetic structure and extends along an object axis using a first probe coupled to the non-magnetic structure and located proximate the target object at a first detection region, the first probe comprising
 an electromagnetic coupler extending in a coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the coupler direction being generally aligned with the bar axis,   a first transmitter connected to the electromagnetic coupler, and   a first receiver connected to the electromagnetic coupler and spaced apart from the first transmitter, wherein the target object, the electromagnetic coupler, the first transmitter and the first receiver form an electromagnetic circuit, and wherein the first attribute is at least one of cover depth and cross-sectional area of the target object, the method comprising:   a) introducing, at the first detection region, a pulsed electromagnetic interrogation signal along the electromagnetic circuit and through the target object using the first transmitter, the first pulsed electromagnetic interrogation signal being based on a pulsed voltage electrical signal provided by an input signal generator;   b) receiving, at the first detection region, a response electromagnetic signal that is induced in the target object and generating a corresponding response electrical signal comprising time information and voltage information using the first receiver;   c) determining the first attribute of the target object at the first detection region based on the time information and the voltage information;   d) generating a corresponding first output signal based on the first attribute; and   e) comparing one of the first output signal and the first attribute, to a stored value for the first detection region to determine if a condition is met.   
     
     
         35 . The method of  claim 34 , further comprising generating a status signal based on the comparing. 
     
     
         36 . The method of  claim 34 or 35 , wherein the input signal generator is configured to generate the pulsed voltage electrical signals automatically according to a pre-arranged schedule, a frequency, or a period. 
     
     
         37 . The method of  claim 34 or 35 , wherein the input signal generator is configured to generate the pulsed voltage electrical signals according to a user input. 
     
     
         38 . The method of any one of  claims 34 to 37 , wherein the stored value is a predefined threshold value. 
     
     
         39 . The method of any one of  claims 34 to 37 , further comprising:
 storing, in memory, each first attribute of the target object at the first detection region, wherein the stored value is a previously-stored first attribute of the target object at the first detection region.   
     
     
         40 . The method of  claim 39 , wherein the previously-stored first attribute of the target object at the first detection region is an initial first attribute of the target object at the first detection region. 
     
     
         41 . The method of  claim 39 , wherein the previously-stored first attribute of the target object at the first detection region is an immediately previous first attribute of the target object at the first detection region. 
     
     
         42 . The method of any one of  claims 34 to 41 , wherein the comparing further comprises:
 comparing the first attribute of the target object at the first detection region to the stored value at the first detection region by calculating one of:
 a difference between the first attribute of the target object at the first detection region and the stored value at the first detection region 
 a percentage change between the first attribute of the target object at the first detection region and the stored value at the first detection region, and 
 a rate of change between the first attribute of the target object at the first detection region and the stored value at the first detection region, 
   to determine if the condition is met.   
     
     
         43 . The method of  claim 42 , wherein the condition is met if:
 the difference,   the percentage change, or   the rate of change,   is greater than or less than a predetermined threshold.   
     
     
         44 . The method of any one of  claims 34 to 43 , wherein the first attribute corresponds to the cross-sectional area of the target object, and wherein determining the first attribute comprises determining a rate of change/slope of a voltage of the response electrical signal with respect to time and comparing the rate of change to a predetermined data set. 
     
     
         45 . The method of  claim 44 , wherein determining the rate of change comprises determining a slope (in dB/s) of a plot of the amplitude of the logarithm of the voltage of the response electrical signal (dB) with respect to time(s) and comparing the slope to predetermined calibration slope values associated with corresponding rebar areas. 
     
     
         46 . The method of  claim 44 or 45 , wherein the determining the cross-sectional area further comprises determining an amplitude of the voltage of the response electrical signal and comparing the amplitude to the predetermined data set. 
     
     
         47 . The method of any one of  claims 34 to 43 , wherein the first attribute corresponds to the cover depth of the target object, and wherein determining the first attribute comprises determining an amplitude of a logarithm of a voltage of the response electrical signal and comparing the amplitude to a predetermined data set. 
     
     
         48 . The method of  claim 47 , wherein determining the amplitude of the logarithm of a voltage of the response electrical signal comprises determining a y-intercept of a plot of the amplitude of the logarithm of the voltage of the response electrical signal (dB) with respect to time(s) and comparing the y-intercept to predetermined calibration y-intercept values associated with corresponding cover depths. 
     
     
         49 . The method of claim  47  or  50 , wherein determining the cover depth further comprises determining a rate of change/slope of a voltage of the response electrical signal with respect to time and comparing the rate of change to the predetermined data set. 
     
     
         50 . The method of any one of  claims 34 to 49 , further comprising:
 repeatedly:
 f) introducing, at the first detection region, a subsequent pulsed electromagnetic interrogation signal along the electromagnetic circuit and through the target object using the first transmitter, the subsequent pulsed electromagnetic interrogation signal being temporally spaced from the pulsed electromagnetic interrogation signal by a time interval, the subsequent pulsed electromagnetic interrogation signal being based on a subsequent pulsed voltage electrical signal provided by the input signal generator; 
 g) receiving, at the first detection region, a subsequent response electromagnetic signal that is induced in the target object and generating a corresponding subsequent response electrical signal comprising time information and voltage information using the first receiver; 
 h) determining the first attribute of the target object at the first detection region based on the time information and the voltage information; 
 i) generating a corresponding subsequent first output signal based on the first attribute; and 
 j) comparing one of the subsequent first output signal and the first attribute, to the stored value for the first detection region to determine if the condition is met. 
   
     
     
         51 . The method of  claim 50 , wherein successive time intervals define a monitoring period for the first probe at the first detection region. 
     
     
         52 . The method of  claim 51 , further comprising:
 iteratively:
 j) determining a relationship in one of the subsequent first output signal and the first attribute, as a function of time over the monitoring period for the first detection region. 
   
     
     
         53 . The method of  claim 52 , further comprising:
 predicting a future value of one of the subsequent first output signal and the first attribute, for the first detection region, based on the relationship.   
     
     
         54 . The method of any one of  claims 34 to 49 , further comprising using a second probe coupled to the non-magnetic structure and located proximate the target object at a second detection region, the second detection region being spaced along the bar axis from the first detection region, the second probe comprising
 a second electromagnetic coupler extending in a second coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the coupler direction being generally aligned with the bar axis,   a second transmitter connected to the second electromagnetic coupler, and   a second receiver connected to the second electromagnetic coupler and spaced apart from the second transmitter, wherein the target object, the second electromagnetic coupler, the second transmitter and the second receiver form a second electromagnetic circuit, the method further comprising:   f) introducing, at the second detection region, a second pulsed electromagnetic interrogation signal along the second electromagnetic circuit and through the target object using the second transmitter, the second pulsed electromagnetic interrogation signal being based on a second pulsed voltage electrical signal provided by the input signal generator;   g) receiving, at the second detection region, a second response electromagnetic signal that is induced in the target object and generating a corresponding second response electrical signal comprising time information and voltage information using the second receiver;   h) determining the first attribute of the target object at the second detection region based on the time information and the voltage information;   i) generating a corresponding second output signal based on the first attribute; and   j) comparing one of the second output signal and the first attribute, to a stored value for the second detection region to determine if the condition is met.   
     
     
         55 . The method of  claim 54 , wherein the second pulsed electromagnetic interrogation signal and the pulsed electromagnetic interrogation signal are introduced simultaneously. 
     
     
         56 . The method of any one of  claims 34 to 49 , further comprising non-destructively monitoring the first attribute of a second target object that is within the non-magnetic structure and extends along a second object axis using a second probe coupled to the non-magnetic structure and located proximate the second target object at a second detection region, the second probe comprising
 a second electromagnetic coupler extending in a second coupler direction between first and second coupler ends, the first and second coupler ends being positioned adjacent the non-magnetic structure and the coupler direction being generally aligned with the second bar axis,   a second transmitter connected to the second electromagnetic coupler, and   a second receiver connected to the second electromagnetic coupler and spaced apart from the second transmitter, wherein the second target object, the second electromagnetic coupler, the second transmitter and the second receiver form a second electromagnetic circuit, the method further comprising:   f) introducing, at the second detection region, a second pulsed electromagnetic interrogation signal along the second electromagnetic circuit and through the second target object using the second transmitter, the second pulsed electromagnetic interrogation signal being based on a second pulsed voltage electrical signal provided by the input signal generator;   g) receiving, at the second detection region, a second response electromagnetic signal that is induced in the second target object and generating a corresponding second response electrical signal comprising time information and voltage information using the second receiver;   h) determining the first attribute of the second target object at the second detection region based on the time information and the voltage information;   i) generating a corresponding second output signal based on the first attribute; and   j) comparing one of the second output signal and the first attribute, to a stored value for the second detection region to determine if the condition is met.   
     
     
         57 . The method of  claim 56 , wherein the second pulsed electromagnetic interrogation signal and the pulsed electromagnetic interrogation signal are introduced simultaneously. 
     
     
         58 . The method of any one of  claims 34 to 36 , wherein the first target object comprises a ferrous rebar.